Acid Stable Bismuth Vanadate for Photo Electrochemical Chlorine Production

Abstract

Despite significant attention, water oxidation remains one of the largest bottlenecks for solar water splitting. This reaction produces a gas of minimal economic value while introducing kinetic losses to the system. While most research focuses on improving the kinetics minimal efforts have been undertaken to conduct other oxidation chemistries. Here we report the use of bismuth vanadate (BiVO4) for photoelectrochemical production of chlorine gas, an oxidation product possessing superior kinetics and higher economic value than the oxygen that results from standard solar water splitting. In order to prevent photo corrosion while operating in the acidic electrolyte (pH 1) an amorphous tungsten oxide protective layer was electrochemically deposited on the nanoporous BiVO4. These devices were able to demonstrate three hours of stable photocurrent while producing chlorine and hydrogen gas. Light absorbers that are stable in acidic solutions have widespread applications as the same solution is ideal for earth abundant materials that carry out the hydrogen evolution reaction taking place at the counter electrode.